摘要:
Substance mixtures comprising (A) vinyl-containing compounds, (B) an active amount of a mixture inhibiting the premature polymerization of the vinyl-containing compounds, comprising (i) at least one N-oxyl compound of a secondary amine which carries no hydrogen atoms on the &agr;-C atoms, and (ii) at least one iron compound, (C) if appropriate nitro compounds, and (D) if appropriate costabilizers, a process for inhibiting the premature polymerization of vinyl-containing compounds (A) and the use of mixture (B), if appropriate as a mixture with nitro compounds (C) and/or costabilizers (D), for inhibiting the premature polymerization of free radical polymerizable compounds and for stabilizing organic materials against the damaging action of free radicals.
摘要:
A process for preventing undesired polymerization is conducted by maintaining an effective concentration of a stabilizer which comprises N-oxyl radicals in a mixture containing ethylenically unsaturated compounds, wherein (i) an electronic signal which correlates with the concentration of the N-oxyl radicals in the mixture is obtained periodically or continuously, (ii) the electronic signal is compared with a reference value, and (iii) addition of a stabilizer to the mixture is controlled according to the comparison (ii). The signal is preferably obtained by ESR measurement. The process permits efficient use of the stabilizer.
摘要:
A mixture contains one or more vinyl-containing compounds as component (A) and, as a further component, a stabilizer (B) which contains one or more readily volatile nitroxyl compounds as component (b1), one or more sparingly volatile nitroxyl compounds as component (b2), if required one or more aromatic nitro compounds as component (b3) and, if required, one or more iron compounds as component (b4). Stabilizers (B) contain the components (b1) and (b2), (b1) and (b2) and (b3), (b1) and (b2) and (b4), and (b1), (b2), (b3) and (b4), and the premature polymerization of vinyl-containing compounds during their purification or distillation is inhibited by a process in which a stabilizer (B) is added or the components of stabilizer (B) are added as individual substances or in at least two groups of the components.
摘要:
A thermoplastic molding material consists of a polycarbonate A and a graft copolymer B, the latter consisting of an elastomer (rubber) (b.sub.1) and a shell (b.sub.2) grafted onto the elastomer.The elastomer (b.sub.1) contains, as copolymerized units, from 35 to 100% by weight of a diene from the group consisting of the conjugated dienes of 4 to 5 carbon atoms, and can contain, as copolymerized units, from 0 to 65% by weight of a monomer from the group consisting of the alkyl acrylates or alkyl methacrylates, where alkyl is of 1 to 8 carbon atoms.The shell (b.sub.2) is obtained in a conventional manner by successive polymerization of the monomers constituting the shell, in two process steps, in the presence of the elastomer (b.sub.1); in a first process step, from 10 to 90% by weight of a mixture of a vinylaromatic hydrocarbon and one or more ethylenically unsaturated monomers which differ from the said hydrocarbon, in a weight ratio of from 90:10 to 60:40, are first incorporated as copolymerized units, followed by the polymerization of from 90 to 10% by weight of a monomer from the group consisting of the alkyl acrylates or of the alkyl methacrylates, where alkyl is of 1 to 8 carbon atoms.The molding material is used for the production of shaped articles.
摘要:
A process is proposed for coagulation of an aqueous polymer dispersion, which comprises, during or after the coagulation, converting the dissolved coagulation salt into an insoluble form.
摘要:
High molecular weight polyphenylene ethers are prepared from monohydric phenols by a conventional polycondensation, by a method in which the resulting polymers are reacted with an epoxide of the general formula (I) ##STR1## where R.sup.1 and R.sup.2 can be identical or different and are each alkyl, cycloalkyl, aryl, aryloxy, alkoxy or carboxyalkyl, each of which may contain a further epoxide group, or C.sub.3 -C.sub.20 -alkyl-substituted amino, or R.sup.1 is hydrogen and R.sup.2 is one of the above groups, or R.sup.1 and R.sup.2 form part of a cycloalkyl ring.
摘要:
Styrene is recovered continuously from a styrene-containing mixture by distillation of the mixture in a cascade of n distillation columns, where (i) a feed stream comprising a stabilizer system is fed into the first column and/or a stabilizer system is introduced into at least one distillation column upstream of the nth distillation column, where the stabiliser system comprises N-oxyl radicals; (ii) a high boiler fraction having a boiling point higher than that of styrene and comprising the stabilizer system accumulates in the bottom of the nth distillation column; (iii) a substream of the high boiler fraction is recirculated and introduced into at least one distillation column upstream of the nth distillation column; (iv) the remainder of the high boiler fraction is discharged from the process.
摘要:
4-Acylaminopiperidine N-oxides IaA.sup.1 B.sup.1 (Ia)where A.sup.1 is hydrogen or an organic radical and B.sup.1 is a radical IIa ##STR1## where R.sup.1 -R.sup.4 are each C.sub.1 -C.sub.4 -alkyl and R.sup.1 and R.sup.2, on the one hand, and R.sup.3 and R.sup.4, on the other hand, may furthermore be bonded to form a 5-membered or 6-membered ring,R.sup.5 is H or C.sub.1 14 C.sub.4 -alkyl andR.sup.6 is H or C.sub.1 -C.sub.18 -alkyl,are used for stabilizing organic materials against the harmful effect of free radicals, particularly in the distillation of monomers which undergo free radical polymerization, especially styrene.
摘要:
Thermoplastic molding materials contain(A) from 5 to 95% by weight of a nylon and(B) from 5 to 95% by weight of a copolymer composed of(B.sub.1) from 50 to 99.9% by weight of a styrene of the general formula I ##STR1## where R.sup.1 is alkyl or 1 to 4 carbon atoms or hydrogen, R.sup.2 is alkyl of 1 to 6 carbon atoms or halogen and m is 0, 1, 2 or 3,(B.sub.2) from 0.1 to 30% by weight of a monomer containing epoxide groups (II) ##STR2## or of a monomer containing lactam groups (III) ##STR3## or of a monomer containing halobenzyl groups (IV) ##STR4## where R.sup.3 is a divalent, branched or straight-chain alkyl group of 2 to 15 carbon atoms, R.sup.4 is alkyl of not more than 6 carbon atoms, X is halogen, n is 1, 2 or 3 and r is 0, 1, 2 or 3, and(B.sub.3) from 0 to 48% by weight of further comonomers.
摘要:
A process is proposed for coagulation of an aqueous polymer dispersion, which comprises, during or after the coagulation, converting the dissolved coagulation salt into an insoluble form.